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CN109997377B - Audio system and method for acoustic isolation - Google Patents

Audio system and method for acoustic isolation Download PDF

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Publication number
CN109997377B
CN109997377B CN201780072361.9A CN201780072361A CN109997377B CN 109997377 B CN109997377 B CN 109997377B CN 201780072361 A CN201780072361 A CN 201780072361A CN 109997377 B CN109997377 B CN 109997377B
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audio
acoustic energy
audio signal
field speaker
mode
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CN201780072361.9A
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CN109997377A (en
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C·奥斯瓦尔德
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Bose Corp
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Bose Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers
    • H04R3/14—Cross-over networks
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R29/00—Monitoring arrangements; Testing arrangements
    • H04R29/001—Monitoring arrangements; Testing arrangements for loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S7/00—Indicating arrangements; Control arrangements, e.g. balance control
    • H04S7/30—Control circuits for electronic adaptation of the sound field
    • H04S7/302—Electronic adaptation of stereophonic sound system to listener position or orientation
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/128—Vehicles
    • G10K2210/1282—Automobiles
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2420/00—Details of connection covered by H04R, not provided for in its groups
    • H04R2420/01—Input selection or mixing for amplifiers or loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/13—Acoustic transducers and sound field adaptation in vehicles

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Multimedia (AREA)
  • Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
  • Stereophonic System (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

The invention provides an audio system and method for providing acoustic isolation. In one example, an audio system includes: an audio source; a first speaker positioned proximate to the first seating position; a second speaker positioned proximate to the second seating location, the second speaker configured to provide acoustic energy to the second seating location based on an audio signal from an audio source; a third speaker positioned proximate to the third seating location, the third speaker configured to provide acoustic energy to the third seating location during the first mode of operation; and at least one cancellation filter interposed between the audio source and the third speaker, the at least one cancellation filter configured to provide a filtered audio signal to the third speaker during the second mode of operation to cancel at least a portion of the acoustic energy provided by the second speaker at the first seating position.

Description

Audio system and method for acoustic isolation
Technical Field
Aspects and implementations of the present disclosure relate generally to audio systems, and in some examples, more particularly to audio systems for providing acoustic isolation in a vehicle.
Background
Conventionally, vehicle audio systems transmit audio signals to speakers positioned in a peripheral surface of a passenger compartment of a vehicle, such as a door or an instrument panel of the vehicle. Audio signals supplied by a vehicle radio (or other signal source) are amplified, processed, and corresponding acoustic energy is transmitted through speakers to convey audio content to occupants of the vehicle. Typical vehicle audio systems deliver common audio content to all occupants of the vehicle regardless of occupant occupancy within the vehicle.
Disclosure of Invention
According to an aspect of the present disclosure, an audio system is provided that includes near-field speakers arranged at a plurality of seating locations within a vehicle. In particular, at least one of the near-field speakers may be operable to substantially reduce acoustic energy leaking from another near-field speaker to an undesired location. Such aspects and implementations are particularly advantageous when included in a vehicle having at least two rows of seats, where acoustic energy from near-field speakers of seats near the rear of the vehicle may undesirably leak to seats at the front of the vehicle (or vice versa).
In particular, the audio system may include at least one near-field speaker positioned near a first seat in the rear of the vehicle that is operable to focus canceling acoustic energy at a seating location in the front of the vehicle to substantially cancel leaked acoustic energy from another near-field speaker positioned in the rear of the vehicle. Thus, each near-field speaker may be dynamically reconfigured between a first mode of operation during which the near-field speaker provides acoustic energy proximate to a seating location, and a second mode of operation during which the near-field speaker provides acoustic isolation functionality (e.g., noise reduction) at another seating location.
According to one aspect, an audio system is provided. In one example, an audio system includes: at least one audio signal source; a first near-field speaker coupled to at least one audio signal source and positioned proximate to the first seating location; a second near-field speaker coupled to the at least one audio signal source and positioned proximate to the second seating position, the second near-field speaker configured to provide acoustic energy to the second seating position based on the audio signal provided by the at least one audio signal source; a third near-field speaker coupled to the at least one audio signal source and positioned proximate to a third seating location, the third near-field speaker configured to provide acoustic energy to the third seating location based on an audio signal provided by the at least one audio signal source during the first mode of operation; and at least one cancellation filter interposed between the at least one audio signal source and the third near-field speaker, the at least one cancellation filter configured to provide a filtered audio signal to the third near-field speaker during the second mode of operation to cancel at least a portion of the acoustic energy provided by the second near-field speaker at the first seating position.
In one example, the audio system further comprises: at least one sensor positioned to detect at least one of an empty and an occupancy of the third seating location and provide a corresponding occupancy signal; and a control circuit coupled to the at least one sensor and configured to select between a first mode of operation and a second mode of operation based at least in part on the occupancy signal. According to some examples, the control circuit is configured to dynamically switch between the first and second operating modes based on the detected occupancy of the third seating position, and the control circuit is configured to dynamically switch between the second and first operating modes based on the detected occupancy of the third seating position.
According to one example, in the second mode of operation, the third near-field speaker is configured to receive the filtered audio signal and radiate cancellation acoustic energy such that the acoustic energy and cancellation acoustic energy provided by the second near-field speaker destructively interfere at the first seating position. In one example, the at least one cancellation filter includes at least one linear time-invariant filter defined by a transfer function. According to one example, the acoustic energy provided by the second near-field speaker includes at least a high frequency portion and a low frequency portion, and the cancelled portion of the acoustic energy provided by the second near-field speaker is the low frequency portion.
In some examples, the at least one cancellation filter is configured such that in the second mode of operation, the third near-field speaker does not generate acoustic energy in a high frequency range associated with the high frequency portion.
According to some examples, the first seating position is located within the first audio content region, the second seating position is located within the second audio content region, the third seating position is located within the second audio content region, and the second audio content region is located within one of a forward direction or a rearward direction of the first audio content region. In one example, the first seating position includes a first seat within the vehicle, the second seating position includes a second seat within the vehicle, and the third seating position includes a third seat within the vehicle.
In one example, the first seat comprises a driver's seat positioned within a first row of seats of the vehicle, the second seat comprises a first rear passenger's seat positioned within a second row of seats of the vehicle, and the third seat comprises a second rear passenger's seat positioned within a second row of seats of the vehicle. According to one example, the first seat comprises a first rear passenger seat positioned within a second row of seats of the vehicle, the second seat comprises a front passenger seat positioned within a first row of seats of the vehicle, and the third seat comprises a driver's seat positioned within the first row of seats of the vehicle.
According to an aspect, an audio system is provided. In one example, an audio system includes: a first audio signal source; a first near-field speaker coupled to an audio signal source and positioned within the first audio content region; a second audio signal source; a second near-field speaker and a third near-field speaker each coupled to a second audio signal source and positioned within the second audio content region, the second near-field speaker configured to provide acoustic energy to the second audio content region based on an audio signal provided by the second audio signal source; at least one sensor positioned to detect an absence of the first seating position within the second audio content zone and proximate to the third near-field speaker; and at least one cancellation filter interposed between the second audio signal source and the third near-field speaker, the at least one cancellation filter configured to provide a filtered audio signal to the third near-field speaker in response to the vacancy detected by the at least one sensor to cancel at least a portion of the acoustic energy provided by the second near-field speaker within the first audio content zone.
In one example, the at least one sensor is further configured to detect occupancy of the first ride location, and the third near-field speaker is further configured to provide acoustic energy to the second audio content zone based on the audio signal provided by the second audio signal source in response to the occupancy detected by the at least one sensor. According to an example, the first near-field speaker is configured to provide acoustic energy to the first audio content zone based on an audio signal provided by the first audio signal source, and the audio signal provided by the first audio signal source is different from a second audio signal provided by the second audio signal source.
According to some examples, the audio system further comprises: control circuitry coupled to the at least one sensor and configured to select between a first mode of operation and a second mode of operation based on the detected vacancy or the detected occupancy, wherein in the first mode of operation, the third near-field speaker is configured to provide acoustic energy to the second region of audio content, and in the second mode of operation, the third near-field speaker is configured to provide cancellation acoustic energy such that the acoustic energy provided by the second near-field speaker and the cancellation acoustic energy destructively interfere within the first region of audio content.
In one example, the acoustic energy provided by the second near-field speaker includes at least a high frequency portion and a low frequency portion, and the cancelled portion of the acoustic energy provided by the second near-field speaker is the low frequency portion. According to one example, the at least one cancellation filter is configured to provide the filtered audio signal to the third near-field speaker to cancel a portion of the acoustic energy provided by the second near-field speaker at a second seating location within the first audio content zone, and the second seating location includes a vehicle seat positioned within a first row of seats of the vehicle. In one example, the at least one cancellation filter is configured to provide the filtered audio signal to the third near-field speaker to cancel a portion of the acoustic energy provided by the second near-field speaker at a second seating location within the first audio content region, and the second seating location includes a vehicle seat positioned within a second row of seats of the vehicle.
According to an aspect, a method of operating an audio system is provided. In one example, the method includes: providing an audio signal; providing acoustic energy from the first near-field speaker to the first seating location in response to receiving the audio signal at the first near-field speaker; selecting between a first mode of operation and a second mode of operation; providing acoustic energy from the second near-field speaker to a second seating position located proximate to the second near-field speaker during the first mode of operation; and canceling at least a portion of the acoustic energy emitted from the first near-field speaker at the third seating location based at least in part on the filtered audio signal provided to the second near-field speaker during the second mode of operation.
In one example, canceling at least a portion of the acoustic energy emitted from the first near-field speaker includes providing canceling acoustic energy from the second near-field speaker such that the acoustic energy provided by the first near-field speaker and the canceling acoustic energy destructively interfere at the third seating location. According to one example, the acoustic energy provided by the first near-field speaker includes at least a high frequency portion and a low frequency portion, and canceling at least a portion of the acoustic energy emitted from the first near-field speaker includes canceling the low frequency portion.
According to an example, the method further comprises: detecting at least one of an occupancy and an vacancy of the second seating location, and providing a corresponding occupancy signal, and selecting between the first mode of operation and the second mode of operation is based at least in part on the occupancy signal. In one example, selecting between the first mode of operation and the second mode of operation includes dynamically switching between the first mode of operation and the second mode of operation based on a detected vacancy of the second seating position. According to one example, selecting between the first mode of operation and the second mode of operation includes dynamically switching between the second mode of operation and the first mode of operation based on a detected occupancy of the second seating position.
Still other aspects, examples, and advantages of these exemplary aspects and examples are discussed in detail below. Examples disclosed herein may be combined with other examples in any manner consistent with at least one of the principles disclosed herein, and references to "an example," "some examples," "an alternative example," "various examples," "one example," etc. are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described may be included in at least one example. The appearances of such terms herein are not necessarily all referring to the same example. Various aspects and examples described herein may include means for performing any of the described methods or functions.
Drawings
Various aspects of at least one example are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. The accompanying drawings are included to provide illustration and a further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the disclosure. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
FIG. 1 is a schematic diagram of an example vehicle audio system, according to aspects of the present disclosure;
fig. 2A-2D are schematic diagrams of a cancellation filter block and a near-field speaker mounted in an associated headrest from the vehicle audio system of fig. 1, according to aspects of the present disclosure; and is
Fig. 3 is an example process flow for acoustic isolation, according to aspects of the present disclosure.
Detailed Description
According to an aspect of the present disclosure, an audio system is provided that includes near-field speakers arranged at a plurality of seating positions. In particular, at least one of the near-field speakers may be operable to substantially reduce acoustic energy provided by another of the plurality of near-field speakers and leaked to an undesired location. In one example, at least one of the near-field speakers may be positioned proximate to the first seating position and may be controlled to substantially reduce acoustic energy leaked by the other near-field speaker and received at the second seating position. Certain examples of near field speakers discussed herein may be operable between at least a first mode of operation during which the near field speaker provides acoustic energy to a corresponding close ride location and a second mode of operation during which the near field speaker provides functionality for an improved listening experience (e.g., noise cancellation) at another ride location. In at least these examples, the detected occupancy or vacancy of the corresponding seating position may prompt reconfiguration between the first and second modes of operation, or vice versa.
According to certain implementations, the audio system may include a near-field speaker positioned at a rear of the vehicle, which may be controlled to cancel acoustic energy leaked by another near-field speaker at the rear of the vehicle to the seating location at the front of the vehicle. In a similar implementation, the audio system may include a near-field speaker positioned at the front of the vehicle that may be controlled to cancel acoustic energy leaked by another near-field speaker at the front of the vehicle to a seating location at the rear of the vehicle. While at least one advantage of the audio systems discussed herein includes improved acoustic isolation, various other benefits and advantages are discussed with reference to the following examples and implementations.
Although elements of several views of the drawings herein may be shown and described as discrete elements in a block diagram and may be referred to as "circuitry," unless otherwise indicated, these elements may be implemented as one of, or a combination of, analog circuitry, digital circuitry, or one or more microprocessors executing software instructions. For example, the software instructions may include Digital Signal Processing (DSP) instructions. Unless otherwise indicated, the signal lines may be implemented as discrete analog or discrete digital signal lines, a single discrete digital signal line with appropriate signal processing capable of processing separate streams of audio signals, or elements of a wireless communication system. Some of the processing operations may be represented according to the calculation and application of coefficients. Equivalent forms of calculating and applying coefficients may be performed by other analog signal processing techniques or digital signal processing techniques and are included within the scope of the present disclosure. Unless otherwise indicated, audio signals may be encoded in digital or analog form; a conventional digital-to-analog converter or analog-to-digital converter may not be shown in the figure.
It is to be understood that the examples of the methods and apparatus discussed herein are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. These methods and apparatus can be implemented in other examples and can be operated or performed in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to "or" may be understood to be inclusive such that any term described using "or" may indicate any single one, more than one, or all of the stated terms. Any reference to front and back, left and right, top and bottom, upper and lower, and vertical and horizontal is for convenience of description, and is not intended to limit the present systems and methods or their components to any one positional or spatial orientation.
Canceling sound (e.g., crosstalk cancellation) may be utilized with near-field speakers to provide discrete audio content zones at different seating locations within a listening area, such as a cabin. A "near-field speaker" may include a speaker located near the head position of an occupant corresponding to a seating position. Fig. 1 shows an exemplary implementation of a vehicle audio system 100 that includes a plurality of crosstalk cancellation filters and a plurality of near-field speakers mounted on a headrest to provide two discrete (front and rear) audio content areas 101a, 101b within a vehicle cabin 103. Although the audio system 100 is shown in the example of fig. 1 as being configured as an audio system installed within the cabin 103, in various other implementations, the audio system may be configured to be installed in other spaces having more than one seating location, such as theaters, ride-on amusement park facilities, auditoriums, and the like.
As shown in fig. 1, the system 100 may include one or more audio signal sources 102 coupled to an audio signal processing circuit 104. The audio signal processing circuit 104 is coupled to a front volume adjusting circuit 106a and a rear volume adjusting circuit 106b, respectively. The front volume adjustment circuit 106a and the rear volume adjustment circuit 106b are coupled to the near-field speakers via cancellation filter blocks, which may include crosstalk cancellation filter blocks 110 a-110 d. While in one implementation, each near-field speaker may be located within a headrest of the seat corresponding to the seating position, as shown in the example system 100 of fig. 1, in other implementations, each near-field speaker may be located at a location coextensive with an exterior of the associated headrest, or at any other suitable location proximate to the seating position and proximate to the head of an occupant (e.g., occupants D0, D1, D2, D3).
In response to control information received from the user via manual input, the control circuit 114 sends a signal 116 to the audio signal processing circuit 104 to select a given audio source for the front audio content region 101a and the rear audio content region 101 b. That is, the signal identifies which audio source is selected for each audio content region. Each audio content region may select a different audio source or a common audio source may be selected for both the front audio content region 101a and the rear audio content region 101 b. In some examples, the audio signal processing circuit 104 transmits a first audio signal 118 representing the audio content of the front region 101a to the front volume adjustment circuit 106a and transmits a second audio signal 120 representing the audio content of the rear region 101b to the rear volume adjustment circuit 106 b. In various examples, the first audio signal 118 is different from the second audio signal 120.
In response to volume control information received from the user via a manual input, the control circuit sends first and second volume control signals 122, 124 to front and rear volume adjustment circuits 106a, 106b, respectively. The front volume adjustment circuit 106a and the back volume adjustment circuit 106b adjust the respective amplitudes of the first audio signal 118 and the second audio signal 120 in response to the volume control signals 122, 124 and provide amplitude adjusted audio signals 126, 128 to the crosstalk cancellation filter blocks 110 a-110 d. In this regard, the front volume adjustment circuit 106a controls the volume of the audio content presented in the front audio content region 101a, and the rear volume adjustment circuit 106b operates to control the volume of the audio content presented in the rear audio content region 101 b. Thus, even if the same audio content is selected for presentation in both zones, the volume level may differ between the zones.
In the illustrated example, the front volume adjustment circuit 106a provides a first amplitude-adjusted audio signal 126 to the first and second crosstalk cancellation filter blocks 110a, 110b, and the rear volume adjustment circuit 106b provides a second amplitude-adjusted audio signal 128 to the third and fourth crosstalk cancellation filter blocks 110c, 110 d. Each of the filter blocks 110 a-110 d includes a plurality of crosstalk cancellation filters that may be implemented as Least Squares (LS) filters. In some examples, each cancellation filter may include a linear time-invariant filter defined by a transfer function. The filter transfer function for the crosstalk cancellation filter may be determined according to:
G＝H-1
wherein,
g is a matrix representing the solved filter transfer function;
h is a matrix representing the measured acoustic transfer function, and H-1Is a pseudo-inverse of the matrix.
The filter transfer function G is combined with the acoustic transfer function H of the system to form a crosstalk cancellation system.
With respect to the example shown in fig. 1, the filter transfer functions for the crosstalk cancellation filters in the first and second filter blocks 110a, 110b may be solved together, as in some examples, the two filter blocks work together to provide crosstalk cancellation at the front seating positions 160a, 160b and to cancel audio from the front region 101a at the rear seating positions 162a, 162 b. Similarly, the filter transfer functions for the crosstalk cancellation filters in the third filter block 110c and the fourth filter block 110d may be solved together, as the two filter blocks may work together to provide crosstalk cancellation at the rear seating positions 162a, 162b and to cancel audio from the rear zone 101b at the front seating positions 160a, 160 b. The crosstalk cancellation filter blocks 110 a-110 d provide respective filtered audio signals 130, 132, 134, 136 to corresponding near-field speaker groups that convert the filtered audio signals 130, 132, 134, 136 to provide acoustic energy and transmit audio content.
As shown in fig. 1, the system 100 may include a pair of front head restraints 140, 142 and a pair of rear head restraints 144, 146. In the illustrated example, each of the front head restraints is provided with four electro-acoustic transducers, including two forward-emitting electro-acoustic transducers (e.g., near- field speakers 148a, 148b, 150a, 150b) and two rearward-emitting electro-acoustic transducers (e.g., near- field speakers 152a, 152b, 154a, 154 b). The forward-emitting speakers 148a, 148b, 150a, 150b of the front headrests 140, 142 provide audible audio content to the occupants D0, D1 (i.e., the two front seating positions 160a, 160b) in the front audio content region 101a, while also assisting in achieving interaural crosstalk cancellation in each of the two front seating positions 160a, 160b, as well as seat-to-seat crosstalk cancellation between the first and second seating positions 160a, 160 b. The rearward-facing transmitting speakers 152a, 152b, 154a, 154b of the front headrests 144, 146 assist in achieving cross-talk cancellation between the front and rear audio content regions 101a, 101 b.
Each of the rear headrests 144, 146 includes two forward-emitting speakers (e.g., near- field speakers 156a, 156b, 158a, 158 b). The forward-emitting speakers 156a, 156b, 158a, 158b of the rear headrests 144, 146 provide audible audio content to occupants (i.e., the two rear seating positions 162a, 162b) in the rear audio content region 101b, while also assisting in achieving interaural crosstalk cancellation in each of the two rear seating positions 162a, 162b, and seat-to-seat crosstalk cancellation between the third and fourth seating positions 162a, 162 b. Operating the forward-firing speakers 148a, 148b, 150a, 150b of the front headrests 140, 142 and the rearward-firing speakers 152a, 152b, 154a, 154b of the front headrests 140, 142 and the forward-firing speakers 156a, 156b, 158a, 158b of the rear headrests 144, 146 in this manner is referred to herein as a first mode of operation of the corresponding near-field speakers.
Referring to fig. 2A, and with continued reference to fig. 1, the first crosstalk cancellation filter block 110a includes a plurality of crosstalk cancellation filters (eight crosstalk cancellation filters are shown). A first amplitude adjusted audio signal 126, shown as a stereo audio signal including a left audio channel 126a and a right audio channel 126b, is passed through a first crosstalk cancellation filter block 110a to produce first filtered audio signals 130a through 130d (collectively 130), one for each of the forward-emitting near- field speakers 148a, 148b, 150a, 150b in the front headrests 140, 142. Each filtered audio signal 130 determines the net acoustic energy associated with each channel of the first audio signal 118 provided to the occupant D0, D1 in the corresponding seating position 160a, 160 b.
Left channel filter 200 associated with forward-firing left speaker 148a of headrest 140, taking into account the acoustic transfer functionL1The left channel input signal 126a is altered from each of the other speakers 148b, 150a, 150b, 152a, 152b, 154a, 154b mounted to the front head restraint to a desired position of the left ear of the occupant D0 to produce a first output signal component configured to reproduce left channel audio content of the first audio signal at the left ear of the occupant D0.
Right channel filter 200 associated with forward-firing left speaker 148a of driver's headrest 140, taking into account the transfer functionR1The right channel input 126b of the first amplitude adjusted audio signal 126 is altered from each of the other speakers 148b, 150a, 150b, 152a, 152b, 154a, 154b mounted in the front head restraint to the desired position of the left ear of occupant D0 to produce a second output signal component configured to cancel the right channel audio content of the first audio signal 118 that leaked from the other speakers 148b, 150a, 150b, 152a, 152b, 154a, 154b in the front head restraints 140, 142 to the left ear of occupant D0.
The first and second output signal components combine to produce a filtered audio signal 130a that is provided to a forward-firing left speaker 148a in the headrest 140. The remaining crosstalk cancellation filters and associated speakers 148b, 150a, 150b of the first crosstalk cancellation filter block 110a operate in a similar manner such that the front audio content zone 101a occupants D0, D1 hear only the left audio content of the first audio signal 118 at their respective left ears and only the right audio content of the first audio signal 118 at their respective right ears.
In some examples, filter 200L2And 200R2Providing the filtered audio signal to the forward-firing right speaker 148b in the headrest 140130b that are converted to reproduce the right channel audio content of the first audio signal 118 at the right ear of occupant D0 while eliminating the left channel content of the first audio signal 118 at the right ear of occupant D0 that is leaked by the other speakers 148a, 150b, 152a, 152b, 154a, 154b mounted in the front headrest.
Filter 200L3And 200R3The forward-firing left speaker 150a in the headrest 142 is provided with a filtered audio signal 130c that is converted to reproduce the left channel audio content of the first audio signal 118 at the left ear of occupant D1 while eliminating the right channel content of the first audio signal 118 at the left ear of occupant D1 that is leaked by the other speakers 148a, 148b, 150b, 152a, 152b, 154a, 154b mounted to the front headrest.
Similarly, filter 200L4And 200R4The forward-firing right speaker 150b in the headrest 142 is provided with the filtered audio signal 130D, which is converted to reproduce the right channel audio content of the first audio signal 118 at the right ear of the occupant D1, while eliminating the left channel content of the first audio signal 118 at the right ear of the occupant D1 that is leaked by the other speakers 148a, 148b, 150a, 152b, 154a, 154b mounted to the front headrest.
Referring to FIG. 2B, and with continued reference to FIG. 1, the second crosstalk cancellation filter block 110B includes a plurality of crosstalk cancellation filters (eight crosstalk cancellation filters are shown). The first amplitude adjusted audio signal 126, again shown as a stereo audio signal including a left audio channel 126a and a right audio channel 126b, is passed through a second crosstalk cancellation filter block 110b to produce second filtered audio signals 132 a-132 d (collectively 132), one for each of the rear-firing near- field speakers 152a, 152b, 154a, 154b in the front headrests 140, 142. These filtered audio signals 132 determine the net acoustic energy associated with each channel of the first audio signal 118 provided by the occupants D2, D3 in the rear seating positions 162a, 162 b.
Associated with the rearwardly-emitting left speaker 152a of the headrest 140, taking into account the acoustic transfer functionLeft channel filter 202L1The left channel input signal 126a is altered from each of the other speakers 148a, 148b, 150a, 150b, 152b, 154a, 154b mounted to the front headrest to a desired position of the left ear of the occupant D2 to produce a first output signal component configured to cancel left channel audio content of the first audio signal 118 that leaks from the other speakers 148a, 148b, 150a, 150b, 152b, 154a, 154b mounted to the left ear of the occupant D2.
The right channel filter 202 associated with the rear-firing left speaker 152a of the headrest 140 takes into account the acoustic transfer functionR1The right channel input 126b from the first amplitude adjusted audio signal is altered from each of the other speakers 148a, 148b, 150a, 150b, 152b, 154a, 154b mounted to the front headrest to a desired position of the left ear of the occupant D2 to produce a second output signal component configured to cancel right channel audio content of the first audio signal 118 leaked from the other speakers 148a, 148b, 150a, 150b, 152b, 154a, 154b mounted to the front headrest to the left ear of the occupant D2.
The first and second output signal components combine to produce a filtered audio signal 132a that is provided to a rear-firing left speaker 152a in the headrest 140. The remaining crosstalk cancellation filters of the second crosstalk cancellation filter block 110b and the associated near- field speakers 152b, 154a, 154b operate in a similar manner such that audio content from the first audio signal 118 is cancelled at the seating positions 162a, 162b of the rear audio content region 101b (fig. 1).
Filter 202L2And 202R2The filtered audio signal 132b is provided to the rear-firing right speaker 152b in 140, which is converted to cancel the audio content of the first audio signal 118 at the right ear of occupant D2 leaked by the other speakers 148a, 148b, 150a, 150b, 152a, 154b mounted on the front headrest.
Filter 202L3And 202R3Providing filtered audio signal 13 to a rear-firing left speaker 154a in headrest 1422c, the filtered audio signal is converted to eliminate audio content of the first audio signal 118 at the left ear of the occupant D3 that is leaked by the other speakers 148a, 148b, 150a, 150b, 152a, 152b, 154b mounted in the front headrest.
Filter 202L4And 202R4The filtered audio signal 132D is provided to the rear-firing right speaker 154b in the headrest 142 of occupant D1, which is converted to cancel the audio content of the first audio signal 118 at the right ear of occupant D3 that is leaked by the other speakers 148a, 148b, 150a, 150b, 152a, 152b, 154a mounted to the front headrest.
Referring to fig. 2C, and with continued reference to fig. 1, the third crosstalk cancellation filter block 110C includes a plurality of crosstalk cancellation filters (eight crosstalk cancellation filters are shown). The second amplitude adjusted audio signal 128, shown as a stereo audio signal including a left audio channel 128a and a right audio channel 128b, is passed through a third crosstalk cancellation filter block 110c to produce third filtered audio signals 134 a-134 d (collectively 134), one for each of the forward-emitting speakers 148a, 148b, 150a, 150b in the front headrests 140, 142. These filtered audio signals 134 determine the net acoustic energy associated with each channel in the second audio signal 120 provided to the occupant of the front seat.
Left channel filter 204 associated with forward-firing left speaker 148a of headrest 140, taking into account the acoustic transfer functionL1The left channel input signal 128a is altered from each of the rear headrest mounted near- field speakers 156a, 156b, 158a, 158b (fig. 1) and from each of the other front-firing near- field speakers 148b, 150a, 150b mounted to the front headrest to the desired position of the left ear of the occupant D0 to produce a first output signal component configured to cancel left channel audio content of the second audio signal 120 that leaks to the left ear of the occupant D0 from the rear headrest mounted speakers 156a, 156b, 158a, 158b and from the other front-firing speakers 148b, 150a, 150b mounted to the front headrest.
Taking into account acoustic transmissionDecreasing function, right channel filter 204 associated with forward-firing left speaker 148a of 140R1The right channel input 128b from the second amplitude adjusted audio signal 128 is altered from each of the rear headrest mounted speakers 156a, 156b, 158a, 158b and from each of the other front emitting speakers 148b, 150a, 150b mounted to the front headrest to the desired position of the left ear of the occupant D0 to produce a second output signal component configured to cancel the right channel audio content of the second audio signal 120 that leaks to the left ear of the occupant D0 from the rear headrest mounted speakers 156a, 156b, 158a, 158b and from the other front emitting speakers 148b, 150a, 150b mounted to the front headrest.
The first and second output signal components combine to produce a filtered audio signal 134a that is provided to a forward-firing left speaker 148a in the headrest 140 of occupant D0. The remaining crosstalk cancellation filters and associated speakers 148b, 150a, 150b of the third crosstalk cancellation filter block 110c operate in a similar manner such that audio content from the second audio signal 120 is cancelled at the seating position of the front audio content region 101a (fig. 1).
Filter 204L2And 204R2The forward-firing right speaker 148b in the headrest 140 is provided with a filtered audio signal 134b that is converted to cancel the audio content of the second audio signal 120 at the right ear of the occupant D0 that is leaked by the other front-headrest mounted speakers 148a, 150b and the rear-headrest mounted speakers 156a, 156b, 158a, 158 b.
Filter 204L3And 204R3The forward-firing left speaker 150a in the headrest 142 is provided with a filtered audio signal 134c that is converted to cancel the audio content of the second audio signal 120 at the left ear of the occupant D1 that is leaked by the other speakers 148a, 148b, 150b mounted in the front headrest and the speakers 156a, 156b, 158a, 158b mounted in the rear headrest.
Filter 204L4And 204R4Forward emitting right speakers into headrest 142The filter 150b provides a filtered audio signal 134D that is converted to eliminate audio content of the second audio signal 120 at the right ear of the occupant D1 that is leaked by the other front headrest mounted speakers 148a, 148b, 150a and the rear headrest mounted speakers 156a, 156b, 158a, 158 b.
Referring to FIG. 2D, and with continued reference to FIG. 1, the fourth crosstalk cancellation filter block 110D includes a plurality of crosstalk cancellation filters (eight crosstalk cancellation filters are shown). The second amplitude adjusted audio signal 128, again shown as a stereo audio signal including a left audio channel 128a and a right audio channel 128b, is passed through a fourth crosstalk cancellation filter block 110d to produce fourth filtered audio signals 136 a-136 d (collectively 136), one for each of the speakers 156a, 156b, 158a, 158b in the rear headrests 144, 146. These filtered audio signals 136 determine the net acoustic energy associated with each channel in the second audio signal 120 provided to the rear seat occupant.
A left channel filter 206 associated with the left speaker 156a of the headrest 144 taking into account the acoustic transfer functionL1The left channel input signal 128a is altered from each of the other speakers 156b, 158a, 158b mounted to the rear headrest and the forward-firing speakers 148a, 148b, 150a, 150b (fig. 1) of the front headrests 140, 142 (fig. 1) to a desired position of the left ear of the occupant D2 to produce a first output signal component configured to reproduce the left channel audio content of the second audio signal 120 at the left ear of the occupant D2.
A right channel filter 206 associated with the left speaker 156a of the headrest 144 of the left rear passenger, taking into account the acoustic transfer functionR1Altering the right channel input 128b from the second amplitude adjusted audio signal 128 from each of the other rear headrest mounted speakers 156b, 158a, 158b and the forward emitting speakers 148a, 148b, 150a, 150b of the front headrests 140, 142 to a desired position of the left ear of the occupant D2 to produce a second output signal component configured to cancel the output from the other rear headrest 156b, 158a, 158b and from the front headrest mounted speakers 156b, 158a, 158bThe forward-emitting speakers 148a, 148b, 150a, 150b in the pillows 140, 142 leak right channel audio content of the second audio signal 120 to the left ear of the occupant D2.
The first and second output signal components combine to produce a filtered audio signal 136a that is provided to a left speaker 156a in the headrest 144. The remaining crosstalk cancellation filters and associated speakers 156b, 158a, 158b of the fourth crosstalk cancellation filter block 110d operate in a similar manner such that occupants of the third and fourth seating positions 162a, 162b hear only the left audio content of the second audio signal 120 at their respective left ears and only the right audio content of the second audio signal 120 at their respective right ears.
Filter 206L2And 206R2The right speaker 156b in the headrest 144 is provided with a filtered audio signal 136b that is converted to reproduce the right channel audio content of the second audio signal 120 at the right ear of the occupant D2 while eliminating the left channel content of the second audio signal 120 at the right ear of the occupant D2 that is leaked by the front-mounted loudspeakers 148a, 148b, 150a, 150b mounted to the front headrest and the other loudspeakers 156b, 158a, 158b mounted to the rear headrest.
Filter 206L3And 206R3The filtered audio signal 136c is provided to the left speaker 158a in the headrest 146, which is converted to reproduce the left channel audio content of the second audio signal 120 at the left ear of the occupant D3, while eliminating the right channel content of the second audio signal 120 at the left ear of the occupant D3 that is leaked by the front-mounted loudspeakers 148a, 148b, 150a, 150b mounted to the front headrest and the other loudspeakers 156a, 156b, 158b mounted to the rear headrest.
Filter 206L4And 206R4The forward-firing right speaker 158b in the headrest 146 is provided with the filtered audio signal 136D, which is converted to reproduce the right channel audio content of the second audio signal 120 at the right ear of the occupant D3, while eliminating the right ear of the occupant D3 from the forward-firing speakers 148a, 148b, 150a, 150b mounted on the front headrest and the rear headrest thereofThe left channel content of the second audio signal 120 leaked by his speaker 156a, 156b, 158 a.
The audio system 100 described above may allow rear occupants of the vehicle (also known as rear passengers), i.e., occupants in the rear seating positions 162a, 162b, to listen to different audio content than occupants in the front seating positions 160a, 160 b. The system 100 may also allow both groups of occupants (i.e., front and rear) to listen to the same audio content at distinct volume levels. For example, passengers in the rear seating positions 162a, 162b may wish to listen to the same audio content at a low volume level as passengers in the front seating positions 160a, 160 b.
When the volume difference between the zones becomes large (-6 dB), there may be some spectral coloration in the attenuation zone (i.e., the lower volume zone) due to relatively poor isolation at higher frequencies. This may be particularly apparent when the same audio content is presented in both audio content zones. In some cases, to suppress such spectral coloration, lower frequencies in the attenuation region may be attenuated less than higher frequencies, which may help flatten the acoustic energy in the attenuation region (i.e., maintain a substantially balanced spectrum) to provide a user experience that feels more like conventional volume control.
Thus, during the first mode of operation, each of the forward emitting speakers 148a, 148b, 150a, 150b of the front headrests 140, 142 and the rearward emitting speakers 152a, 152b, 154a, 154b of the front headrests 140, 142 and the forward emitting speakers 156a, 156b, 158a, 158b of the rear headrests 144, 146 may be controlled to provide an improved listening experience to the corresponding seating positions. Various other examples of crosstalk filters and near-field speakers configured to provide filtered Audio content to near-seating locations are further described in commonly owned U.S. patent application No. 14/828,991 entitled "Audio Systems for Providing Isolated Listening Zones" (filed 8, 18, 2015), which is incorporated by reference herein in its entirety.
In certain other examples, each of the near-field speakers within the audio system 100 may also be driven to provide an improved listening experience at another seating location within the vehicle cabin. For example, referring to fig. 1, the system 100 may dynamically reconfigure one or more of the cancellation filter blocks 110 a-110 d based on the load within the cabin 103 to drive the corresponding speaker to focus the cancellation acoustic energy at a desired location. Such operation is performed during the second mode of operation. During operation of the audio system 100, the system 100 may automatically or dynamically reconfigure each near-field speaker between the first mode of operation and the second mode of operation, or vice versa.
It should be appreciated that within an enclosed space (such as the cabin 130), acoustic energy provided by the near-field speaker may reflect from surfaces proximate the near-field speaker and may undesirably leak to other seating locations. This is typically the case when a seating location is in either a forward or rearward direction of the seating location intended to receive the acoustic energy. For example, audio content provided by the forward-emitting near- field speakers 156a, 156b may be undesirably leaked and received by the occupant D0 at the first seating position 160a and the occupant D1 at the second seating position 160 b.
Thus, in certain examples, the audio system 100 may utilize near-field speakers corresponding to the vacant seating positions to provide canceling acoustic energy that destructively interferes with the leaked acoustic energy at the unintended locations. That is, rather than providing audio content to an empty ride location, the system 100 may drive a near-field speaker corresponding to the empty ride location to provide canceling acoustic energy at another location. An empty indication or occupancy indication (shown generally as signal 164) of one or more seating positions may be received from one or more sensors 166 a-166 d via a sensor interface of the control circuit 114 or manually set by a user. Each empty or occupied indication may specify a near-field speaker available for noise cancellation through the second mode of operation.
As shown in fig. 1, the audio system 100 may include one or more sensors (i.e., sensors 166 a-166 d), each positioned proximate to a seating location within the cabin 103. In response to receiving the indication from the sensor, the control circuit 114 may adjust the front and rear volume adjustment circuits 106a, 106b and/or one or more crosstalk cancellation filters in the filter blocks 110 a-110 d to provide an adjusted filtered audio signal. In particular, in response to receiving an occupancy signal indicating that a particular seating location is empty, the control circuit 114 may adjust one or more coefficients of a transfer function of a crosstalk cancellation filter of one or more near-field speakers corresponding to the empty seating location such that the corresponding near-field speakers provide cancellation acoustic energy. For example, in response to receiving a sensor input indicating that the fourth seating position 162b is empty, the control circuit 114 may vary the coefficients of the transfer functions of the plurality of crosstalk cancellation filters of the cancellation filter block 110d that provides filtered audio signals to the forward-transmitting near- field speakers 156a, 156b, 158a, 158 b.
In various implementations, the one or more sensors 166 a-166 d shown in fig. 1 may include one or more sensors positioned in or around a vehicle seat in a seating position. For example, the one or more sensors 166 a-166 d may include pressure sensors, optical sensors, or any other suitable sensor device. In some cases, the sensor input may be obtained at the control circuitry 114 via a sensor interface of the control circuitry 114. The cross-talk cancellation filter transfer function coefficients may be predetermined based on transfer function measurements made with different occupancy configurations of the cabin 103 and other characteristics of the environment described herein. The coefficients for the different occupancy configurations may be stored in a look-up table accessible to the control circuit 114. The lookup table may include any array that is computed at run-time with an indexing operation. For example, the look-up table may comprise an array of pre-computed and indexed transfer function coefficients stored in a static program storage device.
In some implementations, the control circuit 114 may include a single controller; however, in various other examples, the control circuit 114 may be comprised of multiple controllers and/or control circuits. Although the control circuit 114 is shown separate from one or more components of the audio system 100, in various examples, the control circuit 114 may be combined with one or more other components, such as the audio signal processing circuit 104, the volume adjustment circuits 106a, 106b, and one or more cancellation filter blocks 110 a-110 d. For example, the control circuit 114, the audio signal processing circuit 104, the volume adjustment circuits 106a, 106b, and the one or more cancellation filters 110 may comprise a combination of software configured elements, application specific integrated circuits, or any combination of various hardware and logic circuitry for performing the various processes described herein.
In various examples, the control circuitry 114 includes a processor, a data storage device, a user interface, and one or more interfaces for system components, such as a sensor interface and a communication interface. The processor may be coupled to the data storage device, the communication interface, and one or more other interfaces, and configured to execute a series of instructions that result in the storage and retrieval of operational data from the data storage device. The processor may comprise a commercially available processor, such as the processor manufactured by INTEL, AMD, MOTOROLA, or FREESCALE.
In additional examples, the processor may be configured to execute an operating system. The operating system may provide platform services to the application software. These platform services may include inter-process and network communications, file system management, and standard database operations. One or more of many operating systems may be used, and examples are not limited to any particular operating system or operating system characteristics. In some examples, the processor may be configured to execute a real-time operating system (RTOS) such as RTLinux, or a non-real-time operating system such as BSD or GNU/Linux.
The instructions stored on the data storage device may include executable programs or other code that may be executed by the processor. The instructions may be persistently stored as encoded signals, and the instructions may cause the processor to perform the functions and processes described herein, such as providing one or more control signals to adjust the transfer function coefficients. The data storage device may include information recorded on or in the medium, and the information may be processed by the processor during execution of the instructions. The data storage device includes a computer-readable and writable non-volatile data storage medium configured to store non-transitory instructions and data. Further, the data storage device includes a processor memory that stores data during operation of the processor.
Refer again to FIG. 2D, with continued reference to the figure1, the control circuit 114 may adjust the filter 206 in response to receiving the occupancy signal indicating that the seating position of occupant D3 (i.e., the fourth seating position 162b) is emptyL3、206R3、206L4、206R4Such that the cancellation acoustic energy is concentrated at the seating position of occupant D0 (i.e., the first seating position 160a) to provide enhanced cancellation of the audio content associated with the second audio signal 120 at the seating position 160a (i.e., other than via the speakers 148a, 148b and the filter 204)L1、204R1、204L2、204R2In addition to the cancellation provided). Specifically, the left audio channel 128a and the right audio channel 128b pass through the adjusted crosstalk cancellation filter 206L3、206R3、206L4、206R4To produce filtered audio signals 136c, 136d, one for each of the near- field speakers 158a, 158b in the rear headrest 146. During the second mode of operation, the filtered audio signals 136c, 136d may determine a net acoustic energy associated with substantially reducing the net acoustic energy of each channel in the second audio signal 120 that leaks from at least the near- field speakers 156a, 156b to occupants of the first seating position 160a (and/or the front audio content region 101 a).
Similarly, in response to receiving an occupancy signal indicating that the seating position of occupant D2 (i.e., third seating position 162a) is empty, the control circuit 114 may adjust the filter 206L1、206R1、206L2、206R2Such that the canceling acoustic energy is concentrated at the seating position of occupant D1 (i.e., the second seating position 160 b). Specifically, the left audio channel 128a and the right audio channel 128b pass through the adjusted crosstalk cancellation filter 206L1、206R1、206L2、206R2To produce filtered audio signals 136a, 136b, one for each of the near- field speakers 156a, 156b in the rear headrest 144. During the second mode of operation, the filtered audio signals 136a, 136b may determine a net acoustic energy associated with substantially reducing the net acoustic energy of each channel in the second audio signal 120, which net acoustic energy isAn occupant leaking from the near- field speakers 158a, 158b to the second seating position 160b (and/or the front audio content region 101 a). In other cases, such as when the seating position 160b is unoccupied, speakers (e.g., speakers 150a, 150b) associated with the headrest 142 may be used to provide enhanced attenuation of energy (e.g., low frequency energy) leaking from the front region 101a to the rear seating positions 162a, 162 b.
In another example, with continued reference to the audio system 100 of fig. 1, and with reference again to fig. 2B, in response to receiving an indication that the seating position of occupant D3 (i.e., the fourth seating position 162B) is empty, the control circuit 114 may adjust the filter 202L3、202R3、202L4、202R4Such that the canceling acoustic energy is concentrated at the seating position of occupant D2 (i.e., the third seating position 162 a). In particular, the left audio channel 126a and the right audio channel 126b pass through the adjusted crosstalk cancellation filter 202L3、202R3、202L4、202R4To produce filtered audio signals 132c, 132d, one for each of the near- field speakers 154a, 154b in the front headrest 142. During the second mode of operation, the filtered audio signals 132c, 132d may determine a net acoustic energy associated with substantially reducing the net acoustic energy of each channel in the first audio signal 118 that leaks from the near- field speakers 148a, 148b to the third seating position 162a and/or occupants of the rear audio content region 101 b.
Similarly, in response to receiving an indication that the seating position of occupant D2 (i.e., the third seating position 162a of fig. 1) is empty, the control circuit 114 may adjust the filter 202L1、202R1、202L2、202R2Such that the canceling acoustic energy is concentrated at the seating position of occupant D3 (i.e., the fourth seating position 162b of fig. 1). In particular, the left audio channel 126a and the right audio channel 126b pass through the adjusted crosstalk cancellation filter 202L1、202R1、202L2、202R2To produce filtered audio signals 132a, 132b, one for each of the near- field speakers 152a, 152b in the front headrest 140.During the second mode of operation, the filtered audio signals 132a, 132b may determine a net acoustic energy associated with substantially reducing the net acoustic energy of each channel in the second audio signal 118 that leaks from the near- field speakers 150a, 150b to the third seating position 162a and/or occupants of the rear audio content region 101 b.
In a particular example, the acoustic energy provided by the near-field speakers and leaked to the undesired location may include at least a high frequency portion and a low frequency portion (e.g., acoustic energy leaked from the near- field speakers 156a, 156b to the first seating position 160 a). In such examples, one or more near-field speakers near the vacant seating position may provide canceling acoustic energy to substantially cancel leaked acoustic energy of a certain frequency range. For example, the high frequency portion may be in a frequency range of 500Hz to 5,000Hz, and the low frequency portion may be in a frequency range of 150Hz to 500 Hz. Providing canceling acoustic energy to substantially cancel at least a portion of the acoustic wave leaking to the other seating location may include substantially canceling a low frequency portion of the acoustic energy. The frequency range including the high frequency portion of the leaked acoustic energy may be substantially reduced by one or more volume control functions performed by other components of the audio system 100, such as the volume adjustment circuit 106 b.
While the discussion herein discusses substantially eliminating, substantially reducing, or substantially eliminating a portion of the acoustic energy leaked to the undesired location, it should be understood that the acceptable level of leaked acoustic energy will vary widely based on the application, the level of performance of a given system, and/or the sensitivity level of a particular occupant. Thus, while in at least one example, canceling a portion of the leaked acoustic energy may include canceling all or a majority of the leaked acoustic energy, in various other examples, this may include canceling only a small portion of the leaked acoustic energy.
While discussed with reference to the example audio system 100 of fig. 1 and fig. 2A-2D as including a "front" audio content region 101a and a "rear" audio content region 101b, as well as a "first" seating position 160a, a "second" seating position 160b, a "third" seating position 162A, and a "fourth" seating position 162b, such aspects and embodiments of the audio system 100 may be arranged in orientations other than those shown in the illustrated examples. That is, while in one example the first and second seating positions 160a and 160b are in a forward direction relative to the third and fourth seating positions 162a and 162b, in various other embodiments the first and second seating positions 160a and 160b may be in a rearward direction of the third and fourth seating positions 162a and 162 b. Thus, in various other embodiments, the various seating positions may be positioned at different locations than those shown in fig. 1 and 2A-2D.
As described above, several examples perform processes for controlling acoustic isolation and providing an improved listening experience for occupants of a seating location. In some examples, these processes are performed by an audio system (such as system 100 described with reference to at least fig. 1). One example of such a process is shown in fig. 3.
According to the example shown in fig. 3, process 300 may include the following actions: providing an audio signal; providing acoustic energy from a first near-field speaker; selecting between at least a first mode of operation and a second mode of operation; and in the first mode of operation, providing acoustic energy from the second near-field speaker, and in the second mode of operation, canceling at least a portion of the acoustic energy from the first near-field speaker. Fig. 3 is discussed with continued reference to the example audio system 100 shown in fig. 1 and fig. 2A-2D.
In act 302, process 300 includes providing audio signals from one or more audio sources 102. One or more audio signals may be provided and received at the audio signal processing circuit 104. As described herein, each audio content zone 101a, 101b may select a different audio source. However, in some examples, a common audio source may be selected for the front audio content region 101a and the rear audio content region 101 b. In various examples, the audio signal processing circuit 104 transmits a first audio signal to the front volume adjustment circuit 106a and a second audio signal to the rear volume adjustment circuit 106 b. Typically, this comprises a first audio signal 118 representing the audio content of the front region 101a and a second audio signal 120 representing the audio content of the rear region 101 b.
In various examples, process 300 may also include receiving a control from a user to select a particular audio source for each audio content zone. Such actions may include receiving user input at a user interface of the control circuit 114 indicating a desired audio source for each audio content region. In response to receiving the selection, the control circuit 114 may provide one or more signals to the audio signal processing circuit 104 to initiate an audio signal provision action.
Upon receipt, the volume adjustment circuits 106a, 106b adjust the respective amplitudes of the received audio signals and provide the amplitude adjusted audio signals to the corresponding crosstalk cancellation filter blocks. In this regard, the front volume adjustment circuit 106a controls the volume of the audio content presented in the front audio content region 101a, and the rear volume adjustment circuit 106b operates to control the volume of the audio content presented in the rear audio content region 101 b.
In act 304, the process 300 further includes receiving an audio signal at the first near-field speaker and providing acoustic energy from the first near-field speaker to the seating location proximate to the speaker. For example, the process 300 may include providing acoustic energy (e.g., musical content) from the forward-emitting near- field speakers 156a, 156b in the rear headrest 144 to the third seating position 162 a. As noted above, while each near-field speaker is intended to provide acoustic energy to a seating location proximate the near-field speaker, it should be appreciated that within an enclosed space (such as a vehicle cabin), the provided acoustic energy may reflect off surfaces proximate the near-field speaker and may undesirably leak to other seating locations. For example, music content provided by the near field speakers 156a, 156b may undesirably leak to at least the first seating position 160 a.
While in some cases, the recipient of the leaked acoustic energy may prefer to receive audio content intended for other listeners, the leaked acoustic energy is generally disturbing to those unintended recipients. For example, during extended periods of time within the vehicle, occupants within the front of the vehicle may be bored by listening to movie soundtracks transmitted to occupants in the rear of the vehicle. Thus, in various examples, process 300 includes the following actions: the filtered audio signal is provided to a near-field speaker positioned proximate to another seating location, and at least a portion of the leaked acoustic energy is cancelled based at least in part on the filtered audio signal at an undesired seating location (act 310).
In act 306, process 300 may include selecting between a first mode of operation and a second mode of operation. In the first mode of operation (act 308), the process 300 includes providing acoustic energy from the second near-field speaker to a seating position located proximate to the second near-field speaker. For example, during the first mode of operation, the process 300 may include providing acoustic energy to the fourth seating position 162b from the forward-emitting near- field speakers 158a, 158b within the rear headrest 146. As discussed with reference to at least fig. 1, during the first mode of operation, each speaker is also operable to provide crosstalk cancellation functionality at the corresponding seating position. For example, in the first mode of operation, the near field speakers 158a, 158b may provide acoustic energy to the fourth seating position 162b and may be driven to substantially cancel leaked acoustic energy received at the fourth seating position 106d from any other near field speakers.
In a second mode of operation (act 310), the process 300 may include canceling at least a portion of the acoustic energy leaked from the first near-field speaker while canceling acoustic energy provided by the second near-field speaker at another seating location. For example, in act 310, the process 300 may include updating coefficients of one or more of the crosstalk cancellation filters within one of the filter blocks 110 a-110 d to provide a filtered audio signal to focus cancellation acoustic energy at a desired location. In response to adjusting the cancellation filter and providing the filtered audio signal to the second near-field speaker, corresponding cancellation acoustic energy may be radiated to destructively interfere with leaked acoustic energy from the first near-field speaker. For example, the near field speakers 158a, 158b may receive the filtered audio signals and radiate canceling acoustic energy to help cancel the leaked acoustic energy provided from the near field speakers 156a, 156b at the first seating position 160 a.
As discussed above with reference to at least fig. 1, in various examples, the mode of operation of a given near-field speaker may be based at least in part on the vacancy or occupancy of the corresponding ride location. Thus, in certain examples, the process 300 may include detecting or receiving a selection of at least one of an occupancy and an occupancy of a ride location, and providing a corresponding occupancy signal. Act 312 is shown in fig. 3 as including an act of detecting that the seating location is unoccupied; however, in certain other examples, similar sensors may be placed to detect occupancy of the seating location.
Referring to the first mode of operation, if no vacancy is detected (i.e., occupancy is detected), the process 300 may include continuing the first mode of operation. However, if vacancy is detected (i.e., no occupancy is detected) while operating in the first mode of operation, process 300 may include switching to the second mode of operation. Conversely, referring to the second mode of operation, if no vacancy is detected (i.e., occupancy is detected), the process 300 may include switching to the first mode of operation. However, if an empty is detected in the second mode of operation (i.e., no occupancy is detected), the process 300 may include continuing the second mode of operation.
In various examples, the process may also include certain other actions not shown or discussed with reference to fig. 3. Such acts and processes may include those performed by components of the audio system 100 and discussed with reference to fig. 1, 2A, and 2B.
Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the description. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the disclosure is to be determined from the appropriate construction of the appended claims, and their equivalents.

Claims (24)

1. An audio system, comprising:
at least one audio signal source;
a first near-field speaker coupled to the at least one audio signal source and positioned proximate to a first seating location;
a second near-field speaker coupled to the at least one audio signal source and positioned proximate to a second ride position, the second near-field speaker configured to provide acoustic energy to the second ride position based on audio signals provided by the at least one audio signal source;
a third near-field speaker coupled to the at least one audio signal source and positioned proximate to a third seating location, the third near-field speaker configured to provide acoustic energy to the third seating location based on the audio signal provided by the at least one audio signal source during a first mode of operation; and
at least one cancellation filter interposed between the at least one audio signal source and the third near-field speaker, the at least one cancellation filter configured to provide a filtered audio signal to the third near-field speaker during a second mode of operation to cancel at least a portion of the acoustic energy provided by the second near-field speaker at the first ride position.
2. The audio system of claim 1, further comprising:
at least one sensor positioned to detect at least one of an empty and an occupancy of the third seating location and provide a corresponding occupancy signal; and
a control circuit coupled to the at least one sensor and configured to select between the first mode of operation and the second mode of operation based at least in part on the occupancy signal.
3. The audio system of claim 2, wherein the control circuit is configured to dynamically switch between the first mode of operation and the second mode of operation based on the detected vacancy of the third seating location, and wherein the control circuit is configured to dynamically switch between the second mode of operation and the first mode of operation based on the detected occupancy of the third seating location.
4. The audio system of claim 1, wherein in the second mode of operation, the third near-field speaker is configured to receive the filtered audio signal and radiate cancellation acoustic energy such that the acoustic energy provided by the second near-field speaker and the cancellation acoustic energy destructively interfere at the first seating position.
5. The audio system of claim 4, wherein the at least one cancellation filter comprises at least one linear time-invariant filter defined by a transfer function.
6. The audio system of claim 5, wherein the acoustic energy provided by the second near-field speaker comprises at least a high frequency portion and a low frequency portion, and wherein the cancelled portion of the acoustic energy provided by the second near-field speaker is the low frequency portion.
7. The audio system of claim 6, wherein the at least one cancellation filter is configured such that in the second mode of operation, the third near-field speaker does not generate acoustic energy in a high frequency range associated with the high frequency portion.
8. The audio system of claim 1, wherein the first seating position is located within a first audio content zone, the second seating position is located within a second audio content zone, and the third seating position is located within the second audio content zone, and wherein the second audio content zone is located within one of a forward direction or a rearward direction of the first audio content zone.
9. The audio system of claim 8, wherein the first seating position comprises a first seat within a vehicle, the second seating position comprises a second seat within the vehicle, and the third seating position comprises a third seat within the vehicle.
10. The audio system of claim 9, wherein the first seat comprises a driver's seat positioned within a first row of seats of the vehicle, the second seat comprises a first rear passenger's seat positioned within a second row of seats of the vehicle, and the third seat comprises a second rear passenger's seat positioned within the second row of seats of the vehicle.
11. The audio system of claim 9, wherein the first seat comprises a first rear passenger seat positioned within a second row of seats of the vehicle, the second seat comprises a front passenger seat positioned within a first row of seats of the vehicle, and the third seat comprises a driver's seat positioned within the first row of seats of the vehicle.
12. An audio system, comprising:
a first audio signal source;
a first near-field speaker coupled to the first audio signal source and positioned within a first audio content region;
a second audio signal source;
a second near-field speaker and a third near-field speaker each coupled to the second audio signal source and positioned within a second audio content region, the second near-field speaker configured to provide acoustic energy to the second audio content region based on audio signals provided by the second audio signal source;
at least one sensor positioned to detect an absence of a first seating position within the second audio content zone and proximate to the third near-field speaker; and
at least one cancellation filter interposed between the second audio signal source and the third near-field speaker, the at least one cancellation filter configured to provide a filtered audio signal to the third near-field speaker to cancel at least a portion of the acoustic energy provided by the second near-field speaker within the first audio content zone in response to detection of the vacancy by the at least one sensor.
13. The audio system of claim 12, wherein the at least one sensor is further configured to detect occupancy of the first ride location, and wherein the third near-field speaker is further configured to provide acoustic energy to the second audio content zone based on the audio signal provided by the second audio signal source in response to the occupancy detected by the at least one sensor.
14. The audio system of claim 13, wherein the first near-field speaker is configured to provide acoustic energy to the first audio content zone based on the audio signal provided by the first audio signal source, wherein the audio signal provided by the first audio signal source is different from the second audio signal provided by the second audio signal source.
15. The audio system of claim 14, further comprising control circuitry coupled to the at least one sensor and configured to select between a first mode of operation and a second mode of operation based on the detected vacancy or the detected occupancy, wherein in the first mode of operation the third near-field speaker is configured to provide the acoustic energy to the second audio content region, and wherein in the second mode of operation the third near-field speaker is configured to provide cancellation acoustic energy such that the acoustic energy and the cancellation acoustic energy provided by the second near-field speaker destructively interfere within the first audio content region.
16. The audio system of claim 12, wherein the acoustic energy provided by the second near-field speaker comprises at least a high frequency portion and a low frequency portion, and wherein the cancelled portion of the acoustic energy provided by the second near-field speaker is the low frequency portion.
17. The audio system of claim 12, wherein the at least one cancellation filter is configured to provide the filtered audio signal to the third near-field speaker to cancel the portion of the acoustic energy provided by the second near-field speaker at a second seating location within the first audio content zone, wherein the second seating location comprises a vehicle seat positioned within a first row of seats of a vehicle.
18. The audio system of claim 12, wherein the at least one cancellation filter is configured to provide the filtered audio signal to the third near-field speaker to cancel the portion of the acoustic energy provided by the second near-field speaker at a second seating location within the first audio content zone, wherein the second seating location comprises a vehicle seat positioned within a second row of seats of a vehicle.
19. A method of operating an audio system, the method comprising:
providing an audio signal;
in response to receiving the audio signal at a first near-field speaker, providing acoustic energy from the first near-field speaker to a first ride location;
selecting between a first mode of operation and a second mode of operation;
providing acoustic energy from a second near-field speaker to a second seating position located proximate to the second near-field speaker during the first mode of operation; and
canceling at least a portion of the acoustic energy emitted from the first near-field speaker at a third seating location during the second mode of operation based at least in part on the filtered audio signal provided to the second near-field speaker.
20. The method of claim 19, wherein canceling the at least a portion of the acoustic energy emitted from the first near-field speaker comprises providing canceling acoustic energy from the second near-field speaker such that the acoustic energy provided by the first near-field speaker and the canceling acoustic energy destructively interfere at the third seating location.
21. The method of claim 19 wherein the acoustic energy provided by the first near-field speaker comprises at least a high frequency portion and a low frequency portion, and wherein canceling the at least a portion of the acoustic energy emitted from the first near-field speaker comprises canceling the low frequency portion.
22. The method of claim 19, further comprising:
detecting at least one of an empty and an occupied second seating position; and
providing a corresponding occupancy signal, wherein the selection between the first mode of operation and the second mode of operation is based at least in part on the occupancy signal.
23. The method of claim 22, wherein selecting between the first mode of operation and the second mode of operation comprises dynamically switching between the first mode of operation and the second mode of operation based on the detected vacancy of the second seating position.
24. The method of claim 23, wherein selecting between the first mode of operation and the second mode of operation comprises dynamically switching between the second mode of operation and the first mode of operation based on the detected occupancy of the second seating location.
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